1. Field of the Invention
The invention relates to a communication light detection adapter and a communication light detection structure that are adapted to visually check a used/unused state of optical transmission line by detecting a communication light.
2. Description of the Related Art
Optical communication-related equipment uses a communication light detection technique which is adapted to check a used/unused state (hereinafter, referred to as “communication state”) of an optical transmission line by detecting a communication light in an invisible light range so as to monitor the steadiness of the optical transmission line or to prevent a man-caused erroneous removal of connector.
As an example of the communication light detection technique, a communication light detection structure is known which is adapted to extract as a leak light a portion of communication light transmitting through the optical transmission line, to receive the leak light by a light-receiving element, to thereby detect whether the communication light is transmitted through the optical transmission line or not, and to output the communication state of the optical transmission line so as to allow the operator's visual check (see e.g. JP-A-2009-145676, JP-A-2010-231082, JP-A-2011-013359 and JP-A-2011-013360).
The communication light detection structure is provided with a communication light detection adapter 1600 having an adapter main body 102 and a rotating lid member 1601, as shown in FIGS. 16 and 17. The adapter main body 102 has a light extraction hole 101 for extracting leak light toward the light-receiving element. The rotating lid member 1601 is attached to a shaft 116 formed on the adapter main body 102 so as to be rotatable around the shaft 116 as a pivot point between a closed position to close the light extraction hole 101 and an open position to open the light extraction hole 101.
The rotating lid member 1601 is at the closed position to keep the light extraction hole 101 closed except when checking the communication state of the optical transmission line so as to prevent a foreign body such as a dust from entering the light extraction hole 101.